scholarly journals Effects of the Heat Treatment in the Properties of Fibrous Aerogel Thermal Insulation

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 2001 ◽  
Author(s):  
Ákos Lakatos ◽  
Attila Csík ◽  
Anton Trník ◽  
István Budai
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
Thermal Annealing ◽  
Thermal Insulation ◽  
Structural Changes ◽  
Glass Fibers ◽  
Material Structure ◽  
Scanning Calorimetry ◽  
Plastic Foams ◽  
Isothermal Heat Treatments

Nowadays, besides the use of conventional insulations (plastic foams and wool materials), aerogels are one of the most promising thermal insulation materials. As one of the lightest solid materials available today, aerogels are manufactured through the combination of a polymer with a solvent, forming a gel. For buildings, the fiber-reinforced types are mainly used. In this paper, the changes both in the thermal performance and the material structure of the aerogel blanket are followed after thermal annealing. The samples are put under isothermal heat treatments at 70 °C for weeks, as well as at higher temperatures (up to 210 °C) for one day. The changes in the sorption properties that result from the annealing are presented. Furthermore, the changes in the thermal conductivity are followed by a Holometrix Lambda heat flow meter. The changes in the structure and surface of the material due to the heat treatment are investigated by X-ray diffraction and with scanning electron microscopy. Besides, the above-mentioned measurement results of differential scanning calorimetry experiments are also presented. As a result of using equipment from different laboratories that support each other, we found that the samples go through structural changes after undergoing thermal annealing. We manifested that the aerogel granules separate down from the glass fibers and grow up. This phenomenon might be responsible for the change in the thermal conductivity of the samples.

scholarly journals Thermal characterization of fibrous aerogel blanket

2019 ◽  
Vol 282 ◽  
pp. 01001 ◽  
Author(s):  
Ákos Lakatos ◽  
Anton Trnik
Keyword(s):  
Thermal Annealing ◽  
Thermal Insulation ◽  
Thermal Characterization ◽  
Insulation Material ◽  
Scanning Calorimetry ◽  
Solid Materials ◽  
Plastic Foams ◽  
Isothermal Heat Treatments ◽  
New Buildings

Nowadays, the application of thermal insulation materials both by the existing and by new buildings is one of the most important actions in order to reduce the energy loss of buildings. Besides the use of the conventional insulations (plastic foams and wool materials) aerogel is one of the most promising thermal insulation material. Aerogels, one of the lightest solid materials available today, are manufactured through the combination of a polymer with a solvent forming a gel. For buildings the fibre reinforced ones are the mainly used types. It is produced by adding the liquid-solid solution to the fibrous batting. In this paper changes in the thermal performance of the aerogel blanket will be followed after thermal annealing. The samples will be put under isothermal heat treatments at 70 °C for 6 weeks, as well as they will be put under thermal treatment at higher temperatures (from 70 °C till 210 °C) for 1 day. The changes in the thermal conductivity will be followed by Holometrix Lambda heat flow meter, as well as, Differential Scanning Calorimetry results will be presented. From the measured values, thermal properties will be calculated. In this paper we will try to clarify the role played by thermal annealing in thermal diffusivity.

scholarly journals Influence of thermal annealing on structural properties of silica aerogel super insulation material

2019 ◽  
Vol 142 (1) ◽  
pp. 321-329 ◽  
Author(s):  
Ákos Lakatos ◽  
István Csarnovics
Keyword(s):  
Thermal Properties ◽  
Thermal Annealing ◽  
Thermal Insulation ◽  
Structural Changes ◽  
Heat Treatments ◽  
Thermal Treatments ◽  
Insulation Material ◽  
Structural Modifications ◽  
Construction Market ◽  
Isothermal Heat Treatments

AbstractNowadays, aerogel materials are some of the lightest thermal insulation materials available on the construction market; they are produced by the mixing of polymers with solvents since they create a gel. Insulated fibrous-enhanced forms are the most frequently used ones. The type, which is used for thermal insulation, is usually produced by mixing the glass fiber net with the liquid–solid solution. The present paper talks about the structural modifications caused by heat treatment of the aerogel-reinforced with fiberglass. The aerogel probes were subjected to thermal annealing, and once they got isothermal heat treatments for weeks at 70 °C, moreover, untreated samples were subjected to stepwise thermal treatments between 100 and 250 °C for 1 day. Both the heat treatments were executed in dryer equipment under atmospheric air. Changes both in the structure and in chemical bonds of the untreated and annealed samples were followed. Raman spectra have been obtained for the samples. The structural changes have an influence on the studied material as well as in thermal properties. The structural and thermal properties were put under investigation after executing heat treatments on them. Jumps in the thermal conductivity could be connected with some structural changes. Due to the annealing intensity of the peaks connected with Si–O, crystalline SiO is increased, while CH, CH2, CH3, –OH and others are decreased.

scholarly journals Industrial Thermal Insulation Properties above Sintering Temperatures

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4721
Author(s):  
Amalie Gunnarshaug ◽  
Maria-Monika Metallinou ◽  
Torgrim Log
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
Thermal Insulation ◽  
Fire Protection ◽  
Thermal Transport ◽  
Amorphous Materials ◽  
Transport Theory ◽  
Treatment Temperature ◽  
Dimensional Changes ◽  
Passive Fire Protection

Processing highly flammable products, the oil and gas (O&G) industry can experience major explosions and fires, which may expose pressurized equipment to high thermal loads. In 2020, oil fires occurred at two Norwegian O&G processing plants. To reduce the escalation risk, passive fire protection may serve as a consequence-reducing barrier. For heat or cold conservation, equipment and piping often require thermal insulation, which may offer some fire protection. In the present study, a representative thermal insulation (certified up to 700 °C) was examined with respect to dimensional changes and thermal transport properties after heat treatment to temperatures in the range of 700 °C to 1200 °C. Post heat treatment, the thermal conductivity of each test specimen was recorded at ambient temperature and up to 700 °C, which was the upper limit for the applied measurement method. Based on thermal transport theory for porous and/or amorphous materials, the thermal conductivity at the heat treatment temperature above 700 °C was estimated by extrapolation. The dimensional changes due to, e.g., sintering, were also analyzed. Empirical equations describing the thermal conductivity, the dimensional changes and possible crack formation were developed. It should be noted that the thermal insulation degradation, especially at temperatures approaching 1200 °C, is massive. Thus, future numerical modeling may be difficult above 1150 °C, due to abrupt changes in properties as well as crack development and crack tortuosity. However, if the thermal insulation is protected by a thin layer of more robust material, e.g., passive fire protection to keep the thermal insulation at temperatures below 1100 °C, future modeling seems promising.

scholarly journals The effect of heat treatment on thermal conductivity of paulownia wood

2019 ◽  
Vol 78 (1) ◽  
pp. 205-207
Author(s):  
Z. Pásztory ◽  
S. Fehér ◽  
Z. Börcsök
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
Thermal Treatment ◽  
Thermal Insulation ◽  
Insulation Materials ◽  
Heat Treated ◽  
Paulownia Wood

AbstractThe thermal conductivity properties of wood of Paulownia Clones in Vitro 112 were investigated after heat treatment at temperatures of 180 °C, 200 °C and 220 °C. After the treatment, the density decreased by 5.6, 8.9, and 14.1% for the samples heat-treated at 180 °C, 200 °C and 220 °C, respectively. The decrease in the thermal conductivity was 0, 2.6 and 15.7%, respectively. The thermal conductivity of kiri wood after thermal treatment at 220 °C was 0.064 W/mK, which is almost the same as that of thermal insulation materials.

scholarly journals Crystallization Kinetics and Structural Properties of the 45S5 Bioactive Glass and Glass-Ceramic Fiber Doped with Eu3+

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1281 ◽  
Author(s):  
Agata Baranowska ◽  
Magdalena Leśniak ◽  
Marcin Kochanowicz ◽  
Jacek Żmojda ◽  
Piotr Miluski ◽  
...  
Keyword(s):  
Bioactive Glass ◽  
Crystallization Kinetics ◽  
Glass Ceramic ◽  
Structural Changes ◽  
Glass Fibers ◽  
Glass Structure ◽  
Glass Ceramics ◽  
Luminescent Properties ◽  
Ceramic Fiber ◽  
Scanning Calorimetry

An investigation of the crystallization kinetics of 45S5 Bioglass® using differential scanning calorimetry is presented in this paper. Thermal analysis was performed using the Friedman method. The activation energy and the Avrami index were calculated. The glass samples were subjected to additional controlled heat treatment at 620 °C in order to obtain bioactive glass-ceramics with enhanced mechanical properties. X-ray powder diffraction (XRD) measurements indicated the formation of the glass-ceramic structures of three cyclosilicates: Na4Ca4(Si6O18) or Na6Ca3(Si6O18) or Na16Ca4(Si12O36). Based on middle infrared region (MIR) results, it can be concluded that the crystalline phase present in the tested materials was Na6Ca3(Si6O18) (combeite). Material was doped with Eu3+ ions, which act as a spectroscopic probe for monitoring the structural changes in the glass matrix. The decreasing value of the fluorescence intensity radio parameter indicated symmetry around the europium ions and, thus, the arrangement of the glass structure. The bioactive properties of the examined glass-ceramics were also determined. The bioactive glass fibers doped with Eu3+ were manufactured using two different methods. Its structural and luminescent properties were examined.

Phase changes during heat treatment of electrodeposited WO3, MoO3 and V2O5

1992 ◽  
Vol 50 (1) ◽  
pp. 372-373
Author(s):  
G. Veilleux ◽  
A. Guerfi ◽  
R. G. Saint-Jacques ◽  
Lê H. Dao
Keyword(s):  
Heat Treatment ◽  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Structural Changes ◽  
Specific Treatment ◽  
Ambient Air ◽  
Phase Changes ◽  
Scanning Calorimetry ◽  
Fuel Cell Electrodes

Many transition metal oxides have been studied in the last two decades. By an appropriate chemical or electrical means, ions can be inserted into the structure of these oxides with minimal structural changes. This process known as coloration can easily be reversed. This reversible mechanism is of particular interest in applications such as battery and fuel cell electrodes, chemical sensors, electrochromic displays and catalysts.In this study, films of three transition metal oxides (WO3, MoO3, V2O5) were prepared by electrodeposition. The morphology and the structure of these films were analyzed by transmission electron microscopy (TEM) in their as-deposited states and after heat treatment in ambient air up to 500°C. Previous measurements made by differential scanning calorimetry (DSC) showed exothermic peaks corresponding to phase changes. The temperature values determined at those peaks were then chosen as specific treatment temperatures.

scholarly journals Thermal Diffusion in Fibrous Aerogel Blankets

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 823 ◽  
Author(s):  
Ákos Lakatos ◽  
Anton Trník
Keyword(s):  
Thermal Properties ◽  
Thermal Annealing ◽  
Thermal Insulation ◽  
Sol Gel ◽  
Theoretical Background ◽  
Design Stage ◽  
Scanning Calorimetry ◽  
Insulation Materials ◽  
Sol Gel Process ◽  
Transient Thermal

Nowadays, the usage of thermal insulation materials is widespread not only in the building sector but also in the vehicle industry. The application of fibrous or loose-fill insulation materials like glass wool or mineral wool as well as aerogel is well known. Aerogel-based materials are among the best solid materials for thermal insulation available today; they are prepared through a sol–gel process. For building walls, the glass-fiber-enhanced types are the frequently used ones. They are prepared by adding the liquid–solid solution to the fibrous batting, which is called a sol–gel process. In the present paper, the changes in the most important building physical properties of aerogel blankets after thermal annealing are presented. The samples were subjected to isochronal heat treatments from 70 to 210 °C for 24 h. The changes in the thermal conductivity were followed by Holometrix Lambda heat flow meter, and differential scanning calorimetry results were also recorded. From the measured values, together with the densities, the most important thermal properties were calculated, such as thermal resistance, diffusivity, effusivity (heat absorption), and thermal inertia. In this paper, we attempt to clarify the role played by thermal annealing in the transient thermal properties of aerogel materials. Besides presenting the measurement results, a theoretical background is given. The investigations of not only the steady-state but also the transient thermal parameters of the materials are momentous at the design stage.

scholarly journals Study of Industrial Grade Thermal Insulation at Elevated Temperatures

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4613
Author(s):  
Amalie Gunnarshaug ◽  
Maria Monika Metallinou ◽  
Torgrim Log
Keyword(s):  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Heat Fluxes ◽  
Inorganic Materials ◽  
Scanning Calorimetry ◽  
Industrial Grade ◽  
Heat Treated ◽  
In Fire

Thermal insulation is used for preventing heat losses or heat gains in various applications. In industries that process combustible products, inorganic-materials-based thermal insulation may, if proven sufficiently heat resistant, also provide heat protection in fire incidents. The present study investigated the performance and breakdown temperature of industrial thermal insulation exposed to temperatures up to 1200 °C, i.e., temperatures associated with severe hydrocarbon fires. The thermal insulation properties were investigated using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and by heating 50 mm cubes in a muffle furnace to temperatures in the range of 600 to 1200 °C with a 30 min holding time. The room temperature thermal conductivity was also recorded after each heat treatment. Upon heating, the mineral-based oil dust binder was released at temperatures in the range of 300 to 500 °C, while the Bakelite binder was released at temperatures in the range of 850 to 960 °C. The 50 mm test cubes experienced increasing levels of sintering in the temperature range of 700 to 1100 °C. At temperatures above 1100 °C, the thermal insulation started degrading significantly. Due to being heat-treated to 1200 °C, the test specimen morphology was similar to a slightly porous rock and the original density of 140 kg/m3 increased to 1700 kg/m3. Similarly, the room temperature thermal conductivity increased from 0.041 to 0.22 W/m∙K. The DSC analysis confirmed an endothermic peak at about 1200 °C, indicating melting, which explained the increase in density and thermal conductivity. Recently, 350 kW/m2 has been set as a test target heat flux, i.e., corresponding to an adiabatic temperature of 1200 °C. If a thin layer of thermally robust insulation is placed at the heat-exposed side, the studied thermal insulation may provide significant passive fire protection, even when exposed to heat fluxes up to 350 kW/m2. It is suggested that this is further analysed in future studies.

scholarly journals Aerogel, a high performance material for thermal insulation - A brief overview of the building applications

2019 ◽  
Vol 111 ◽  
pp. 06069 ◽  
Author(s):  
Larisa Meliță ◽  
Cristiana Croitoru
Keyword(s):  
Thermal Conductivity ◽  
Thermal Insulation ◽  
High Performance ◽  
Sol Gel ◽  
Research Work ◽  
Solid Material ◽  
Good Choice ◽  
High Price ◽  
Material Structure ◽  
Liquid Component

In this paper data regarding the utilization of aerogel as a promising material for thermal insulation of the residential and commercial buildings are presented. Also, research work and developments in synthesis, properties and characterization of silica aerogels will be addressed. Aerogel is a synthetic porous ultralight material derived from a gel in which the liquid component of the gel has been replaced with a gas. The result is a solid with extremely low density and low thermal conductivity. Sol-gel is the most used method of preparation. Aerogel melts at 1200ºC and the thermal conductivity is almost 0. Is a solid material with the smallest density because contains about 99.8% air. This material has almost unlimited potential, believing that they might find application in most human activities and areas. Aerogel insulation is a good choice because nearly neutralizes all three methods of heat transfer: convection, conduction and radiation. The resistance to convective transfer is given by the fact that air does not circulate in the material structure. The resistance to thermal transfer by conduction is given by the majority of gaseous components. If using a carbon based gel, a high resistance to radiation transfer is obtained. Therefore, the most used aerogel for thermal insulation is the silica aerogel with carbon as nanostructured material. The high price makes it currently inaccessible and less used material. But, inevitably, the aerogel will quickly become one of the most attractive materials in the future.

The Effect of Thermal Activation of Glauconite on its Water-Retaining and Oil Capacity

2019 ◽  
Vol 23 (7) ◽  
pp. 42-47
Author(s):  
S.I. Niftaliyev ◽  
Yu.S. Peregudov ◽  
N.Ya. Mokshina ◽  
R. Mezhri ◽  
I.A. Saranov
Keyword(s):  
Heat Treatment ◽  
Differential Scanning Calorimetry ◽  
Water Vapor ◽  
Water Absorption ◽  
Thermal Activation ◽  
Structural Changes ◽  
Petroleum Products ◽  
Original Sample ◽  
Scanning Calorimetry ◽  
Thermally Activated

The results of the study of the efficiency of heat treatment of samples of glauconite are presented. Estimated ability of the sorbent to water absorption and retention of petroleum products. It was established by the method of differential scanning calorimetry that thermally activated glauconite samples are practically not saturated with water vapor. Oil capacity decreases after heat treatment of glauconite at 600°C and increases at 1000°C compared with the original sample, which is explained by various structural changes.

Sign in / Sign up

Export Citation Format

Share Document